Halogen-containing phosphoric acid catalyst and method of preparing same



United States Patent 3,391,087 HALOGEN-CONTAlNING PHOSPHORIC ACIDSATALYST ANH) METHOD 0F PREPARING AME William G. Nixon, Clcarwater, Fla,assignor to Universal Oil Products Company, Des Plaines, llL, acorporation of Delaware N0 Drawing. Continuation-impart of applicationSer. No. 350,682, Mar. 10, 1964. This application Nov. 17, 1966, Ser.No. 594,978

11 Claims. (Cl. 252-435) ABSTRACT OF THE DISCLOSURE Preparation ofcatalyst by impregnating a solid support with a phosphoric acid, heatingto at least about 500 C., and thereafter heating to about 300600 C. withhydrogen halide or ammonium halide to combine about 1.0- 25% halogenwith the hydroxyl groups of the acid, and the catalyst thus prepared.

This application is a continuation-in-part of my copending applicationSer. No. 350,682, filed Mar. 10, 1964, now abandoned.

This invention relates to the manufacture of a novel hydrocarbonconversion catalyst and particularly to the manufacture of a novelhydrocarbon conversion catalyst comprising a solid phosphoric acidcontaining composite that has been chemically combined with a halogenderived from the hydrogen halides or ammonium halides so as to produce anovel catalytic composition of matter.

It is therefore an object of this invention to provide a method forpreparing a novel hydrocarbon conversion catalyst. A further object ofthis invention is to provide a novel catalytic composition of matter.

One embodiment of this invention resides in a method for the preparationof a catalyst which comprises heating a solid phosphoric acid-containingcomposite with a hydrogen halide or an ammonium halide at a temperatureof from about 300 C. to about 600 C. and chemically combining thehalogen of said halide with the hydroxyl groups of the phosphoric acidin an amount of from about 1.0 to about 25% by weight.

A further embodiment of this invention resides in a catalyst consistingessentially of a solid phosphoric acidcontaining composite having fromabout 1.0 to about 25% by weight of halogen in chemical combination withthe hydroxyl groups of the phosphoric acid.

Other objects and embodiments will be found in the following furtherdetailed description of the invention.

As hereinbefore set forth, the invention is concerned with a method forthe preparation of a catalyst which possesses a high degree ofhydrocarbon conversion activity in, for example, the isomerization of acyclic para'tlins, naphthenes, olefins and alkyl aromatics, thealltylation of alkylatable aromatic compounds with olefin-actingcompounds and the polymerization of unsaturated organic compounds. Thecatalyst comprises a phosphoric acidcontaining composite that iscombined with a halogen to effect chemical combination of the hydroxylgroup of phosphoric acid portion of said composite with said halogen.The composite, if desired, may comprise a high surface area solidsupport although it is one of the features of the catalyst of thepresent invention that low surface area supports such as alpha-aluminaare satisfactory for the preparation of catalysts for use in the processof this invention.

As set forth hereinabove, the support may comprise a high surface areasupport. By the term high surface area is meant a surface area measuredby surface adsorption techniques within the range of from about 25 toabout 500 or more square meters per gram and preferably a support havinga surface area of approximately 100 to 300 square meters per gram.However, as set forth hereinbefore, alpha-alumina, which is usuallycharacterized by a surface area ranging from about 10 to about 25 squaremeters per gram is also a satisfactory support. Therefore, satisfactorysupports for the preparation of catalyst for use in the process of thisinvention include high surface area crystalline alumina modificationssuch as gamma, etaand thetaalumina and low surface area supports such asalpha-alumina, although these are not necessarily of equivalentsuitability. In addition to the aforementioned alpha-, gamma-, etaandthetaaluminas which may be utilized as solid supports, it is alsocontemplated that other refractory oxides such as silica, zirconia,magnesia, thoria, etc. and combinations of refractory oxides such assilica-alumina, silica-magnesia, alumina-silica-magnesia,alumina-thoria, alumina-zirconia, etc. may also be utilized as solidsupports for the catalyst of the present invention.

As set forth hereinabove, the catalyst comprises a phosphoricacid-containing composite that is combined with a halogen to effectchemical combination of the hydroxyl groups of the phosphoric acidportion of said composite with said halogen. The phosphoricacid-containing composite may be made by combining an acid of phosphorussuch as ortho-, pyro-, or tetraphosphoric acid with the solid support.Orthophosphoric (H POQ and pyrophosphoric acid (11 F 0 find generalapplication due mainly to the cheapness and to the readiness with whichthey may be procured although the invention is not restricted to theiruse, but may employ any of the other acids of phosphorus insofar as theyare adaptable. However, it is not intended to infer that the differentacids of phosphorus which may be employed will produce catalysts whichhave identical effects upon any given organic reactions as each of thecatalysts produced from different acids any by slightly varyingprocedures will exert its own characteristic action.

Triphosphoric acids, which may be represented by the formula H P O mayalso be used as one of the starting materials for the preparation of thecomposite utilized in the catalyst of this invention.

A phosphoric acid mixture which is generally referred to aspolyphosphoric acid may also be employed in manufacturing the composite.Polyphosphoric acid is formed by heating orthophosphoric acid orpyrophosphoric acid or mixtures thereof in suitable equipment such ascarbon lined trays heated by flue gases or other suitable means toproduce a phosphoric acid mixture generally analyzing from about 79% toabout 85% by Weight of. P 0

Tetraphosphoric acid, having the general formula H P G Which correspondsto the double oxide formula 3H O.2P O may be considered as the acidresulting when three molecules of water are lost by four molecules oforthophosphoric acid, H PO The 'tetraphosphoric acid may be manufacturedby gradual or controlled d: hydration or heating of orthophosphoric acidand pyro phosphoric acid or by adding phosphorus pentoxide to theseacids in proper amounts.

The phosphoric acid-containing composite utilized in the presentinvention may contain from about 8% or lower to about 80% by weight ofphosphoric acid, and preferably from about 10% to about 50% by weight ofphosphoric acid. Prior art solid phosphoric acid catalytic compositesusually contain from about 50 to about by weight of phosphoric acidcomposited with the solid carrier (such as Mavity US. Patent No.2,584,102) since lower acid contents cause the solid phosphoric acidcatalytic composite to suffer from a hydrocarbon conversion activitystandpoint while those with too high a content of phosphoric acid havepoor structural strength. Solid phosphoric acid catalytic compositeshave been manufactured by prior art methods with from about 15% to about75% by weight of phosphoric acid but compress-ion pressure ranging fromabout 5,000 to about 50,000 pounds per square inch during themanufacturing process have been found necessary to give the catalystincreased structural strength.

It is therefore a feature of the present invention that the phosphoricacid-containing composite utilized in the present invention may containless than about 50% by weight of phosphoric acid without causing thehydrocarbon conversion activity of the finished catalyst to suffer andwithout the need for subjecting the composite to high compressionpressures during manufacture in order to give the catalyst increasedstructural strength inasmuch as the finished catalyst of the presentinvention prepared as hereinafter set forth has increased structuralstrength and a high degree of stability due to the immobility of thecomponents of the finished catalyst inasmuch as chemical combination ofthe phosphoric acid portion of the compositive with the halogen isaccomplished as hereinafter described.

Halogens which may be chemically bound to the phosphoric acid portion ofthe phosphoric acid-containing composite may be incorporated therein inany suitable manner. However, the halogen must be added in a form whichwill readily chemically react with the phosphoric acid portion of saidphosphoric acid-containing composite in order to obtain the desiredcatalytic composite. Therefore, halogen may be added as fluorine,chlorine, bromine and/or iodine but in view of the fact that halogensper se are generally difiicult to handle, it generally is preferable toutilize a halogen derived from the group consisting of hydrogen halidessuch as hydrogen fluoride, hydrogen chloride, hydrogen bromide and/orhydrogen iodide and ammonium halides such as ammonium fluoride, ammoniumchloride, ammonium bromide and/or ammonium iodide. In any case,following the chemical combination of the halogen with the hydroxylgroups of the phosphoric acid portion of the phosphoric acid-containingcomposite, the composite is heat treated. Heat treating the compositeafter chemical reaction of the halogen with the phosphoricacid-containing composite Will drive off, for example, ammonia if anammonium halide is utilized thereby allowing the halogen to remalnimpregnated on and chemically bonded to the phosphoric acid portion ofthe phosphoric acid-containing composite.

The catalyst of the present invention therefore comprise a halogenchemically combined with the phosphoric acid portion of the composite soas to effect chemical combination of the hydroxyl groups of thephosphoric acid with the halogen, and as hereinbefore set forth, it isthe particular association of these components which results in theunusual catalytic properties of the catalyst.

The chemical addition of the halogen to the phosphoric acid portion ofthe phosphoric acid-containing composite will enhance the surface areacharacteristics of the composite inasmuch as the finished catalyticcomposite exhibits greater surface area than the phosphoricacid-containing composite originally possessed. Further, the finalcatalytic composite obtained by the preparation as described hereinaboveis substantially anhydrous due to the chemical combination of thehalogen with the phosphoric acid-containing portion of the composite.Thus, it is another feature of the present invention that asubstantially anhydrous support initially is not necessary to preparethe catalyst of the present invention. Still another feature of thepresent invention is that the final catalytic composite does not needhydration during processing as does a phosphoric acid-containingcomposite as is taught in the prior. art (such as Mavity US. Patent No.2,584,102) inasmuch as the final catalytic composite of my invention issubstantially anhydrous and thus deterioration of a physical nature byprocessing factors tending to further dry the catalyst is not a probl min the present invention.

As hereinbefore set forth, certain forms of alumina may be utilized assupports for the catalyst of this invention. For example, alumina may beprepared by any of the well known suitable means of manufacture, oneexample of which is the addition of an alkaline reagent to a salt ofaluminum in an amount sufiicient to form aluminum hydroxide, which, upondrying and calcining, is converted to alumina. Similarly, if the solidsupport comprises both alumina and silica, these components may beprepared by separate, successive or coprecipitate means.

For example, a phosphoric acid-containing composite previously preparedby the methods hereinabove set forth is then chemically combined with ahalogen such as the halo en derived from treating the composite withammonium chloride, said ammonium chloride being added in an amountsufficient to allow the finished catalytic composite to contain fromabout 1.0 to about 25% or more by weight of halogen. Following this, thechemically combined material is then heat treated in a furnace tube ormufiie furnace or the like. The finished catalytic composite comprisingthe halogen chemically combined with the phosphoric acid portion of thephosphoric acidcontaining composite is then utilized as the hydrocarbonconversion catalyst.

The following examples are introduced for the purpose of illustrationonly with no intention of unduly limiting the generally broad scope ofthe present invention.

Example I In this example, polyphosphoric acid is treated with ammoniumhydroxide to a pH of approximately 9.0 and this solution is impregnatedon the solid support, namely gamma-alumina. The impregnated support isthen heated in a furnace tube to a temperature of about 500 C. andmaintained at this temperature for a period of about 2 hours while heattreating the composite. During the heat treatment of the composite tothe desired temperature, it will be noted that ammonia gas is evolvedfrom the composite thereby leaving phosphoric acid d posited on therefractory oxide support. This phosphoric acidcontaining compositecontaining approximately 50% by weight of phosphoric acid is thensubjected to chemical reaction at a temperature in the range of fromabout 300 C. to about 600 C. with a halogen derived from hydrogenchloride. The finished catalyst will contain about 8.0 weight percent ofchloride. This catalyst is designated as catalyst A.

Example II Another catalyst is prepared by impregnating silica withanother polyphosphoric acid-ammonium hydroxide solution. The impregnatedsupport is then heat treated in a furnace tube to a temperature of above500 C. and kept thereat for a period of about 2 hours. It is noted thatammonia gas is evolved from the composite thereby leaving phosphoricacid deposited on the refractory oxide support. This phosphoricacid-containing composite containing approximately 30% by weight ofphosphoric acid is then subjected to chemical reaction with a halogenderived from ammonium chloride. The resultant composite is again slowlyheat treated in the furnace tube to about 600 C. and once again theevolution of ammonia gas takes place leaving the halogen chemicallycombined with the phosphoric acid portion of the silica support. Thiscatalyst is designated as catalyst B.

Example III Yet an other catalyst is prepared by impregnating silicawith another polyphosphoric acid-ammonium hydroxide solution. Theimpregnated support is then heat treated in a furnace tube to atemperature of about 500 C. and kept thereat for a period of about 2hours. It is noted Example IV In this example, a catalyst is prepared byimpregnating alumina with another polyphosphoric acid-ammonium hydroxidesolution. The impregnated support is then heat treated in a furnace tubeto a temperature of about 500 C. and kept thereat for a period of about2 hours. It is noted that ammonia gas is evolved from the compositethereby leaving phosphoric acid deposited on the refractory oxidesupport. This phosphoric acid-containing composite containingapproximately 38% by weight of phosphoric acid is then subjected tochemical reaction with a halogen derived from ammonium floride. Theresultant composite is again slowly heat treated in the furnace tube toabout 600 C. and again the evolution of ammonia gas takes place leavingthe halogen chemically combined with the phosphoric acid protion of thealumina support. This catalyst is designated as catalyst D.

I claim as my invention:

1. A method for the preparation of a catalyst which comprisesimpregnating a solid support with a phosphoric acid, heating thephosphoric acid-containing composite at a temperature at least about 500C. to deposit the acid on the support and thereafter heating with ahydrogen halide or an ammonium halide at a temperature of from about 300to about 600 C. and chemically combining the halogen of said halide withthe hydroxyl groups of the phosphoric acid in an amount of from about1.0 to about 25 by weight.

2. The method of claim 1 further characterized in that said halide ishydrogen chloride.

3. The method of claim 1 further characterized in that said halide ishydrogen fluoride.

4. The method of claim 1 further characterized in that said halide ishydrogen bromide.

'lit

5. The method of claim 1 further characterized in that said halide isammonium chloride.

6. The method of claim 1 further characterized in that said halide isammonium fluoride.

7. A catalyst prepared by impregnating a solid support with a phosphoricacid, heating the phosphoric acid-containing composite at a temperatureat least about 500 C. to deposit the acid on the support and thereafterheating with a hydrogen halide selected from the group consisting ofhydrogen fluoride, hydrogen bromide and hydrogen iodide at a temperatureof from about 300 C. to about 600 C. and chemically combining thehalogen or" said halide with the hydroxyl groups of the phosphoric acidin an amount of from about 1.0 to about 25% by weight.

8. The catalyst of claim 7 further characterized in that said hydrogenhalide is hydrogen fluoride.

9. The catalyst of claim 7 further characterized in that said hydrogenhalide is hydrogen bromide.

10. A catalyst prepared by impregnating a solid support with aphosphoric acid, heating the phosphoric acid containing composite at atemperature at least about 500 C. to deposit the acid on the support andthereafter heating wih an ammonium halide at a temperature of from about300 C. to about 600 C. and chemically combining the halogen of saidhalide with the hydroxyl groups of the phosphoric acid in an amount offrom about 1.0 to about 25% by weight.

11. The catalyst of claim 10 further characterized in that said ammoniumhalide is ammonium fluoride or ammonium chloride.

References Cited UNITED STATES PATENTS 2,409,247 10/1946 Brooks et al.260683.15 2,428,741 10/1947 Plank 252435 2,584,102 2/1952 Mavity 2524352,596,497 5/1952 Mavity 252-435 2,843,640 7/1958 Langlois et al. 252-4372,938,874 5/1960 Rosinski 252-437 3,213,034 10/1965 Drehman 252-435DANIEL E. WYMAN, Primafy Examiner.

PAUL E. KONOPKA, Assistant Examiner.

